The head of the commission examining the potential break-up of Britain's biggest banks is expected to say today that significant reforms are needed.
Sir John Vickers is set to use a speech in London to give an insight into the investigation by the Independent Commission on Banking into competition in the sector.
It is understood he will say the commission is considering plans to split investment banks from high street deposit-taking institutions.
The Independent Commission on Banking - which was unveiled by George Osborne last June - was created to consider reforms to the banks that would "promote financial stability and competition".
Its aim is to make policy recommendations with a view to reducing the likelihood and impact of banks collapsing, and to consider the competitive advantage held by larger institutions deemed "too big to fail".
But no final decisions have been made, and the commission has until September to make its recommendations to the Government.
Sir John, the former head of the Office of Fair Trading, is chairman of the five-person commission.
The other members are Martin Taylor, a former chief executive of Barclays; Clare Spottiswoode, the former director general of Ofgas; Bill Winters, former co-chief executive of JP Morgan Investment Bank, and Martin Wolf, the chief economics commentator at the Financial Times.
Sir John is speaking at a London Business School conference this afternoon.